In 3D modeling, a mesh’s structure is defined by vertices, edges, and faces (polygons). A non-manifold edge occurs when more than two faces share a single edge. This topology can create problems during various operations such as smoothing, subdivision surface modeling, and 3D printing. Visualize it as a point where three or more sheets of paper meet along a single crease.
Clean mesh topology, free of such non-manifold edges, is crucial for predictable and reliable results in most 3D applications. Issues arising from these edges can range from visual artifacts and shading errors to failures in Boolean operations and simulations. Historically, identifying and correcting these issues has been a vital step in the 3D modeling workflow, and robust tools for this purpose have become increasingly important with the rising complexity of 3D models.
